Although former ONE Lightweight World Champion Kotetsu Boku’s family was from South Korea, he was brought up in Japan. He started boxing at the age of 18, and embarked on his professional martial arts career when he was 22. An eccentric and colorful character, Boku does not fit the norm of a regular athlete, being a vegan who likes to spend his spare time drawing.
His martial arts skills, however, are undeniable. After winning a regional title with Shooto, he would go on to shock the world by knocking out Zorobabel Moreira on his ONE Championship debut to become the inaugural ONE Lightweight World Champion. Boku soon became feared for his punching power, with all of his victories in ONE Championship to date coming by way of knockout.
In 2015, Boku dropped to featherweight for the first time, after spending his entire career taking on bigger opponents in the lightweight division. That proved to be a wise decision, as he has since registered stoppage victories over Timofey Nastyukhin, Major Overall, and Eric Kelly to establish himself as a real force to be reckoned with in a second weight class.